Ordinarily in the Mass, the priest wears three types of sacred vestments:
Alb: This garment is common to both ordained and instituted members of the Church. The Alb is a long white garment that is worn over ordinary clothing. Often, a cincture is used around the waist so that the alb can fit properly.
Chasuble: This is a vestment that comes in many colors and the priest wears the particular color of the liturgical season. The Chasuble is worn over the alb and stole.
Stole: The stole is worn by the priest around his neck. It is a long, narrow rectangular vestment that will also bear the color of the liturgical season. (Please note: a stole is also worn by the deacon, but he wears it across his chest.)
For more information on the different vestments, see Chapter IV of the Constitution on the Sacred Liturgy.